An ion generator ionizing vapor present in a space has conventionally been known. Some of the ion generators employ creeping discharge. In the conventional ion generator, when an alternating voltage is applied to an ion generating element, positive ions and negative ions are generated. It is known that these generated positive and negative ions eliminate molds, airborne fungi or viruses in the air.
Japanese Patent Laying-Open No. 2003-083593 (Patent Document 1) discloses a technique to apply such an ion generator to an air conditioner so as to suppress molds. The air conditioner disclosed in Japanese Patent Laying-Open No. 2003-083593 generates positive and negative ions from the ion generator, and determines whether or not dehumidification or cooling/heating should be performed in accordance with detected temperature or humidity in the room.
The air conditioner disclosed in Japanese Patent Laying-Open No. 2003-083593 generates positive and negative ions from the ion generator whenever it is driven. Therefore, a constant amount of positive and negative ions is generated regardless of the temperature or humidity in the room.
In general, among the viruses, influenza virus is known to attain a high survival rate at low temperature and low humidity. Accordingly, in an environment in which viruses are more likely to proliferate, concentration of ions in the room should desirably be higher than in an environment in which viruses are less likely to proliferate.
[Patent Document 1] Japanese Patent Laying-Open No. 2003-083593